Solenoid actuating reversing valve



Sept 2, 1952 l.. H. GARDNER 2,608,995 SOLENOID ACTUATING 'REVERSING VALVE I l Filed may 1, 194e f l s sheets-sheet 1 sam/Vom 24 ,y 7) 45),??? ,en N .f I l i4 i f4 M k Wl" I Y gf J// @EL M au/randa H kfzyefc" Sept. 2, 1952 L. H. GARDNER SOLENOID ACTUATING REVERSING VALVE 5 Sheets-Sheet 2 Filed May 1, 1946 .SOLENO/ IN V EN TOR.

lf/ @y f Sept. 2, 1952 1 H. GARDNER 2,608,995

SOLENOID ACTUATING REVERSIN VALVE Filed May l, 1946 3 Sheets-Sheet 5 M0 SOL E NO/ D BY a@ 'tomplate thereof omitted; and

Patented Sept. 2, 1952' SOLENOID ACTUATING REVERSING VALVE Lawrence Gardner, Detroit, Mich., assgnor to Automatic Valve, Inc., Farmington, Mich., a

corporation of Michigan Application May 1, i946, Serial No. 666,269

Claims. l

This invention relates to valves and has particular reference to valves suited for continuous high speed operation for controlling fluid pressure. As used herein the term fluid pressure contemplates a liquid or gas under pressure.

Principal objects of the invention are to provide: Y

A new and improved valve of the character disclosed; Y

A new and improved high speed solenoid actuated air control valve; Y

A valve of the character disclosed which is more efijcient in operation, which has a wider range of utility, and which is relatively simple in construction as compared with valves of this type heretofore known. y

Other and'further objects of the invention will be apparent from the following description and claims and will be understood by reference to the accompanying drawings, of which there are three sheets, which by way of illustration show preferred embodiments and the principles thereof and what I now consider to be the best mode in which I have contemplated applying those principles. Other embodiments of the invention embodying the same or equivalent principles may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention and the purview of the appended claims. I also contemplate that of the several different features of my invention, certain ones thereof may be advantageously employed in some applications 'separate and apart from the remainder of the features.

Inthe drawings:

Fig. 1 is a vertical sectional view of a valve embodying the invention, taken generally on the line II---l of Fig. 2, but with certain parts broken of one end of the thereof; Y

Fig. 5 is a top plan view of the device;

Fig. 6 is a sectional View taken generally along the line 6 6 ofFig. 1;

Fig'. 7 is a somewhat diagrammatic View similar to Fig. 1, showing the valve parts with the solenoid deenergized anda connected work cylinder with the ram thereof in; 3'

Fig. 8 is a View. similar to Fig. 7 butv showing the arrangement of the parts with the solenoid energized and the ram out;

Fig. `9 is a sectional view of a valve embodying a modified'form of the invention with the botpressure fiuid, such as air.

Fig. l0 is a bottom plan view of the device as shown in Fig. 9.

Referring now to Figs. l to 8, a valve embodying the invention comprises a valve body or casing '2U provided with chambers 22, 24, 2t, 28 and 36. The main supply chamber 26 is provided with a fluid inlet port 32 connected to a suitable source of high A wall defining the chamber 26 is provided with a duct or pressure supply passage 34, and a valve comprising ,a seat 3E and a valve member 38 is provided for controlling the flow of fluid from the chamber 26 through the duct 34 and into the transfer chamber 28. The chamber 28 is provided with an outlet port liti leading to a work cylinder on one side of the piston or ram thereof.

A plate 42 secured to the bottom of the valve body 2i! is provided With a cross duct 54 which establishes communication between the fluid pressure inlet port 32 vand the auxiliary supply chamber 22 so that the chamber 22, like the chamber 25, is supplied with fluid under pressure and at line pressure.

A wall defining the chamber 22 is provided with a valve seat 46 around a duct or pressure supply passage 43 leading to the transfer chamber 2i. A normally closed valve member 50 is cooper-able with the seat 46 for controlling the flow of fluid under pressure through the duct i3. The valve member 50 comprises a piece of resilient material, such as rubber, fixed' by a pin 52 to member 5d which is freely, slidably a1'- ranged in the cup-shaped member 56, which in turn is threadedly secured in position Vin a threaded opening in the casing or cylinder block 29. A spring 58 arranged between the members 5A and 5G biases the valve member 50 to its seat. The sliding t between the members 54 and 5B is such that there is no dash pot action. The chamber 25 is provided with a port 6i] leading to the work cylinder on the other side of the piston thereof.

The exhaust chamber 3G and the transfer chamber 28 are in part defined by a cup-shaped member t2 which is seated and secured in a bore in the casing 2i), the transverse wall of the members 62 separating the chamber 30 from the chamber 2@ and being apertured as shown in Fig. 6 to define a duct or exhaust passage 64 between such chambers. The duct 64 is composed of fourv slots separated by arms the inner surfaces of kwhich are finished to form a sliding support for one end of the transfer valve member 68.-

The face of the transverse portion of the cupshaped member 62 exposed to the chamber 23 rforms a valve seat 10 for cooperation with a valve member l2.. The valve members 12 ,and l38 are annular rings of resilient material car.-

ried on opposite circular faces of an enlarged annular portion 14 of the valve member 68. A gasket 16 is arranged in an exterior groove in the cup-shaped member 62 so as to form a seal betweenvlthe outer surfaces f the cupshaped member '82 and the inner surface of the bore in which it is arranged.

The chamber 30 is provided with an exhaustJ port 18 forming an atmospheric vent. A -piston valve member 80 is reciprocably arranged in the bore of the cup-shaped member 6'2, -the periph!- ery of the piston being provided -with a groove in which an O-ring packing or sealing member 82 is arranged. This sealing `nlember A'may .be of the type disclosed in Christensen Patent No. 2,180,795, issued November 2l, 1939, for Packing. The piston 80 forms a valve member, and one -face thereof is cooperable `withra valve seat 84 lin the form of an annular resilient .ring arranged fon one -.end .of the valve member 1&8.

The :transfer 'valve :member :6;8 .comprises .a .hollow-tubular .member-which is .reciprocably .mounted Vin -Lthe -.body :'20, .one .end thereof being 'supportedbyrthe =inner .surfaces of .the :arms Bias previously described, While .the .other end thereof is slidably arranged 1in a bore extending :between the chambers 24tand126. An O-ringzpacking '85 isarranged .in a peripheral groove in the vvalve member 68 for-.cooperation with the :bore in .which the -va'lve .member lisis -slidably mountedfso as to establish a seal between the .valve vmember '68 and fthe bore in .the -valve body :between the chambers 24 and 26.

The valve member -68 is hollow and forms a duct I)88, one end .of which .opens Vinto the exhaust chamber 30 on one vside of the piston .80 thereof, .While the other Aend of such duct opens into the chamber .24 lthrough .ports 89. The lastmentioned end-ofthe valve member 68 is provided with an extension 90 which is .adapted .to .project through the duct 48 and engage the head .of the pin 52 securing the -valve vmember 50 imposition for unseating such valve member from its VSeat -when Athe -valve member 68 .moves to the right from `the position shown in Fig. 1.

A solenoid |00 and a .pilot valve .are provided for-controlling rthe operation .of the `valves just described, `the pilot valve .comprising Va slidable pin |.02,1ball valves |04 and 106, and valve .seats '|08` and 0. The body 20 is provided with -a stepped vbore il I3 in `line with .the reciprocating member y|12 .of the solenoid |00. vThe pin |02 .and the'ballvalves |04 and |13? are arranged in such ystepped bore so that the -valve |86 Iwill be seated on the -valve seat ||0 or the valve |04 will .be seated on the seat |08.

Aspring H4 is confined between the ball valve |04 and the member ||2 and biases the ball valve |04 toward its seat |08. Likewise, a spring H@ confined between the ball valve 4.06. and .the end-plate H18 biases the `.ball valve |05 toward its seat.

In Vthe position shown in Figures 1 and 7, the solenoid -is deenergized whereby the spring ||6 is holding the ball valve |018 on its seat ||0. A duct |20 affords communication between chamber 26 anda vchamber |22 which .communicates with the stepped bore `behind the ball valve |06. The valve 0.6 while on its seat prevents vthe llow of uid pressure .from the chamber |22 past the ball valve |106. A duct |24 affords communication :between the chamber 30 and .the reduced portion of the stepped bore between the valve seats ||0 and |08. An atmospheric vent |26 communicates with the portion .of :the bore in which the ball valve |04 is arranged so that with the valve arranged as illustrated in Figures 1 and 7, the chamber 30 will be vented to atmosphere through the duct |24, the stepped bore, andthe atmospheric vent |26.

`When the solenoid |00 is energized the member ||2 will through the spring ||4 seat the ball valve |04 on its seat |08, thereby closing the Acommunication -of the chamber 30 through the duct |24 to atmosphere, and at the same time unseating .the valve '|06 so as to permit the sup- Ply Qf iluid under pressure from the chamber v|22through the duct |24 to the chamber 30.

Reference may now be had to Figs. 7 and 8 wherein the two positions of the valve parts with reference to the work cylinder are illustrated. The parts as arranged in Fig. 7 correspond generally with :thearrangement .of the par-.ts shown in Fig. 1. In Figs. 7 and 8 .the high ypressure air has been indicated lby dots. The ducts and chambers the valve l and the vWork cylinder' filled withlowzpressure air have been .left blank.

lFrom Fig. 7 "it 'will be noted `that .Thigh rpressure uid, such as air, is being supplied tothe chambers 26 `and 22, the `duct' |20, the 'chamber |22, the chamber 28, the conduit 3| leading fto the work cylinder |33, and such work cylinder on one side of the ram 0r 4piston 1.35. thereof'. The lwork cylinder A13.3 l,on the other :side of the ram 1.3,5 thereof :is bei-ng :vented to atmosphere through conduit ;|.31,f.chambe.r 24, duct 8B. lchamber v30, and atmospheric exhaust port 1.8.

The chamber 30 on the other side :ofthe valve member .80 V,is .also being vented .to atmosphere through duct L24, bor-e113 land vent |26.

Energization of the solenoid 1100 will .cause the. member I11.2 thereof V.toseat the ballsvalve |04 on its seat and Vto unseat the ball vali/e106 thereby supplying fluid nunder 'pressure from .the chamberV |22 through the duct v|24 to the :cham ber :30 on one sirle of `the piston 8.0 thereof, thereby causing the piston or valve :member to seat on the valve seat :84fon the end -ojf the valve member 6:8., .thus .closing the duct :88 to atmosphere.

Continued movement of the valve memberl 80 in the same vdirection will shift the valve member -68 to the right `thereby unseating vthe valves 7.2 and 50 and hence seating 4the valve member 138 on its seat. .Unseating of .the `valve '|12 will connect the chamber 28 and the.l conduitV |.3l on one side of the work cylinder. |33 with atmosphere. Unseating .of vthe valve 'member 50 will permit high pressure fluid in the chamber 22 toxow into chamber 24 and through conduit |31 to the work cylinder |33 for the purpose of `moving the ram 1| 35 thereof to the other end of the cylinder or to perform a work stroke. Seat-'- ing of the valve member 38 will close off the supply of fluid under pressure to the conduit |'3|.

YDeenergization of .the solenoid vwill restore .the parts to the position as shown in Fig. 7. Unseating of `the .ball valve |04 and seating of the ball valve |06 will serve to vent -the chamber 30 to atmosphere through the ductv |24 and the vent |26. whereby the airv under pressure in the .duct 88 will unseat the valve member 80 from 'its valveseat .84 and the valve member 38 from its valve seat, thereby closing the communication from the chamber 28 to atmosphere 'While establishing an atmospheric venting forA the duct 88 and the conduit |31.

In the .construction shown in Figs. '9 and 10 the construction is similar to the foregoing Yand the same reference numerals are applied thereto tions it is'desirable to use `a lower pressure air toV move the piston of thework cylinder in one direction than is employed to move such work piston in the opposite direction. r

In Fig. 9 the bottom plate ofthe valve has been omitted, and Fig. 10 shows the ports in the bottom face of the valve body 20. In Figs. 9 and 10 the same reference characters have been employed as used in connection with the previous modification to designate corresponding parts.

The valves may be actuated by some means other than a solenoid, although Where high speed operation is desired a solenoid forms avery effective Way of obtaining high speed operation of the valve. The particular constructionas illustrated, and including the relativel size of the parts, the ducts and the air ports, makes such valve extremely emcient and'dependable in operation.

While I have illustrated and described preferred embodiments of my invention, it is understood' that'these are capable of modification, and

I therefore do not Wish to be limited to the precise details set forth, but desire to avail myself of such changes and alterations as fall vwithin the purview of the following claims.

I claim:

1. A fluid pressure control valve comprising a main supply chamber, an auxiliary supply chamber, ports for admitting fiuid under pressure to said chambers, a first transfer chamber, a. second transfer chamber, ports for Aconnecting said transfer chambers respectively to opposite ends of a work cylinder, an exhaust chamber, an outlet port connecting said exhaust chamber to atmosphere, a first pressure supply passage connecting said main supply chamber to said rst transfer chamber, an exhaust passage connecting said .first transfer chamber to said exhaust chamber, a second pressure supply passage connecting said auxiliary supply chamber to said second transfer chamber, a normally closed valve controlling said secondpressure supply passage, a tubular transfer valve open at its ends and connecting said second transfer chamber and said exhaust chamber, said transfer valve including .valve portions arranged upon shifting of said transfer valve to alternately open and close said .first pressure supply passage and to correspond- Yend of said piston from the open end of said transfer valve, and passages connecting said control port alternately'to pressure and exhaust.

f 3; A valve as defined in claim 2 in which said last mentioned passagesV include a passage connecting said main supply chamber and said exhaust chamber and an exhaust passage, and valve means operable to close one or the other but not both of said pass-ages. Y

4. A valve as defined in claim l in which said chambers are arranged in alignment with said main supply chamber immediately between said transfer chambers, said auxiliary supply chamber is beyond said second transfer chamber, and said exhaust chamber is beyond said first transfer chamber, and said tubular transfer valveinterconnects said second transfer chamber and said exhaust chamber and extends through said main supply chamber Yand said first transfer chamber.

5. A valve as defined in claim 4 in which said rst pressure supply passage and said exhaust passage are constituted by openings at opposite ends of said first transfer chamber in which said transfer valve is movable, and the valve portions of said transfer valve are constituted by'opposite sides of a radially extending flange movable alternately into seating relation with opposite ends o-f said first transfer chamber surrounding the openings. i

6. A valve as defined in claim l in which a passage is provided connecting said main and. auxiliary supply chambers.

'7. A valve as defined in claim 1 in which said main and auxiliary supply chambers are isolated from each other and supplied with fluid at dif ferent pressures. l

8. A fluid pressure control valve comprising a casing having a first chamber adapted to be connected to a source of pressure fluid,l a second chamber adapted to be connected to a work cylinder on one side of the piston thereof, a duct affording communication between said chambers', a third chamber having ports at opposite ends thereof, exhaust passages connected to said ports, and exhaust valve controlling outflow through one of said passages, a duct affording communication between said third and lsecond chambers, each of said ducts terminating in a valve seat in said second chamber, a fourth chamber adapted to be connected to said work cylinder on the other side of the piston thereof, a fifth chamber arranged to be connected to a source of pressure fluid, a duct affording communication between said last two mentioned chambers and having a normally closed valve arranged to be opened for establishing communication between said chambers through said duct, valve members in said second chamber movably mounted to alternately seat on said valve seats therein for alternately closing said ducts communicating with said chamber, a piston valve member reciprocably mounted in said third chamber, said chambers and interconnecting ducts being arranged in alignment, a bore extending between said first and fourth chambers and in alignment with said ducts, a reciprocable hollow valve member open at its ,opposite ends and extending through said ducts chamber being fixed to and movable with said hollow valve member, one end of said hollow valve member beingA engageable with saidnormally closed valve which controls the communication;.between said-fourth `and fifth chambers foropeningfthesame,andmeans includinga :passage -betweenesaid Vfirst chamber .and the Vend of said `third chamber whichcontains the port .connected to said one exhaustpassagdandapressure control valve infsuch passage for Acontrolling the V-flow .of ffluidunderpressurefrom said-first to said thirdchamber whereby when said valve vin such-:passage is open and' -said' exhaust .Valve Vis closed :fluid under pressurein rsaid third `chamber will -be effective onfthe-.fpiston valve member therein to seat-said :piston valve :member .on the Valvexseat .around the V.passage through said -hollow valvefmember, :and to shift said hollow valve member sofas to unseat the valvemember thereon controlling the communication through the `duct between said second `and third chambers -in-order .toyvent the side of saidwork cylinder which is connected to 4said -second chamber; and so as to cause 'the w'alve Jmember thereon to seat .on the valyeseat controlling the communication through the -duct betweensaid first and second chambers in e'order to shut off Vthe supply of pressure fluid tothe last mentioned side of said workcylinder; andvxso -as -to unseat the normally closed valve member from its valve seat in order toA supply pressure fluid from said vfifthchamber through said fourth chamber to the lother side of said work cylinder. e v n Y.

1 9. A Vfluid pressure control valve according to claim 8 wherein a part of said passage between said rst and third chambers forms a part of said one exhaustI passage connected to said third chamber, .and said exhaust valve is arranged to control fluid flow in such a manner that when thev pressure control valve controlling said passage between said first and third chambers is open, said exhaust valve controlling exhaust flow from .said third chamber through said last mentioned passage is closed and vice Versa.

Y 10. A fluid pressure control valve according to claim 8 wherein the other end of said hollow valve member communicates with said fourth chamber so, as to Vent the other side of said work cylinder to atmosphere when said piston valve member is unseated from the valve seat on the end of said hollow valve member yin said third chamber.

1.1. A fluid pressure control valve according to claim 8 wherein a solenoid is arranged to repeatedly unseat said pressure control valve in said passage controlling the flow of fluid under pressure `from said first to said third chamber.

12. A fluid pressure control valve according to claim 8 wherein a part of said passage between said first and third chambers forms a part of said one exhaust passage connected to said third chamber, said exhaust valve is arranged to con- 'trol fluid flow in such a manner that when the pressure control valve controlling said passage between said first and third chambers is open, said exhaust valve controlling exhaust flow from said third chamber through said last mentioned exhaust passage is closed and vice Versa, and means are provided for alternately unseating said pressure control valve in the passage between said first and third chambers and said exhaust valve controlling exhaust flow from said third chamber through said last mentioned exhaust passage.

'13. A fluid pressure control valve according to claim 8 wherein a duct interconnects said first and fifth chambers.

14. A fluid pressure control valve according to claim 8 wherein said fifth chamber is provided 7.5 lclaim 16 wherein said means for supply fluid 'unwith .fluid under '-a lower pressure than that. suppliedrtdsaidffirst chamber. Y i A `15A fluidgpressurefccntrol valve according to claim `8 fwhere'inthe area-of the vport controlled by the valveseataround the'passage through the hollow -valve member is materially less than the areaof the. piston Valve member on the -side there.- of remote from suchvalve seat.

A16. vA fluid .pressure control valve comprising avcasi'ngv having a first chamber connected to a fluid supply :port and forming a fluid pressure chamber, a second chamber adapted to bev connected to a work cylinder-on one side of the.pis ton thereof, a duotaffording4 communication lbetween said chambers, a third chamber having ports -at opposite ends theredf,exhaust .passages connected to said ports, .an exhaust valve coni.- trolling outflow ythrough one of -said passages. -a duct affordingv communication between said. second chamber and the end of said third. chamber at which said other exhaust port is located, `a valve seat in said second chamber associated with each of said ducts, a fourth chamber adapted to be connected to said work cylinder on the other side of the .piston thereof, a fifth chamber -arrangedV to be connected to a source of pressure fluid, a duct affording communication between said last two mentioned chambers and having a valve arranged to be vunse'ated for establishing communicationbetween said chambers through said duct, valvefmembe'rs insaid 'second chamber movablymounted to alternately seat on .saidvalve seats. therein for alternately closing `said ducts communicating .with vsaid second chamber, 'a piston valve member reciprocably mounted in said third chamber, a bore extending between said first and fourth chambers, a vreciprocable hollow valve member open at its opposite ends and ex.- tending through said ducts and bore and between said third and fourth chambers and having a valve seat around the passage through the hollow valve member around the end thereof in said third chamber for seating said piston valve memfber in said third chamber, said valve members in saidsecond chamber being xed to and movable with said hollow valve member, one end of said hollow valve member being engageable with said valve which controls the communication be# 'tween said fourth and fth chambers for opening the same, and means for supplying fluid under pressure to said third chamber on the side of said piston valve member thereof remote from the valve seat on said hollow valve member whereby fluid under pressure in said third chamber will be effective on the piston valve lmember therein to seat said piston valve member on the lvalve seat around the Vpassage through said hollow valve member, and to shift said hollow valve member so as to unseat the valve member thereon controlling the communication through the duct between said second and third chambers in order to vent the side of said work cylinder which is connected to said second chamber; and so as to 'cause the valvev member thereonl to seat on the valve'seatcontrolling the communication through thefduct between said flrst and second chambers in order to shutoff the supply of pressure fluid to thelastfmentioned sideof said work cylinder; and so as tovuns'eatthe 'valve member from the valve seat controlling the flow throughthe duct between the fourth and fifth 'chambers in order to; supply pressure fluid'to the other side 'of said work cylinder. A

17. A fluid pressure control valve according to der pressure to said third chamber has associated therewith means for intermittently venting such side of said third chamber to atmosphere.

18. A fluid pressure control valve according to claim 16 wherein the other end of said hollow valve member communicates with said fourth chamber so as to vent the other side of said work cylinder ot atmosphere when said piston valve member is unseated from the valve seat on the end of said hollow valve member in said third chamber.

19. A iiuid pressure control valve according to claim 16 wherein a duct interconnects said rst and fifth chambers.

20. A fluid pressure control valve according to claim 16 wherein said fifth chamber is provided with fluid under a lower pressure than that supplied to said rst chamber.

21. A fluid pressure control valve according to claim 16 wherein the area of the por-t controlled by the valve seat around the passage through the hollow valve member is materially less than the area of the piston valve member on the side thereof remote from such valve seat.

22. A fluid pressure control valve comprising a casing having a first chamber adapted to be connected to a source of pressure iiuid, a second chamber adapted to be connected to a work cylinder on one side of the piston thereof in order to supply pressure fluid -to such cylinder to perform a work stroke, a duct affording communication between said chambers, a third chamber having ports a-t opposite ends thereof, exhaust passages connected to said ports, an exhaust valve controlling outflow through one of said passages, a duct affording communication between said third and second chambers, each of said ducts terminating in a valve seat -in said second chamber, a fourth chamber adapted to be supplied with pressure fluid, a bore between said third and fourth chambers, valve members in said second chamber movably mounted to alternately seat on said valve seats therein for alternately closing said ducts communicating with said chamber, a piston valve member reciprocably mounted in said third chamber, a reciprocable hollow valve member open at its opposite ends and extending lthrough said ducts and through said bore between said third and fourth chambers and having a valve seat around the passage through the hollow valve member around the end thereof in said third chamber, said valve members in said second chamber being fixed to and movable with said hollow valve member, and means including a passage between said rst chamber and the end of said third chamber which contains the port connected to said one exhaust passage, and a pressure control valve in such passage for controlling the flow of fluid under pressure from said rst to said third chamber whereby when said pressure control valve in such passage is open and said exhaust valve is closed, fluid under pressure in said 10 third chamber will be effective on the piston valve member therein to seat said piston valve lmember on the valve seat around the passage through said hollow valve member, and to shift said hollow valve member so as to unseat the valve member thereon controlling the communication through the duct between said second and third chambers in order to vent the side of said work cylinder which is connected to said second chamber; and so as to cause fthe valve member thereon to seat on the valve seat controlling the communication through the duct between said first and second chambers in order to shut off the supply of pressure uid to the last mentioned side of said vwork cylinder.

23.Y A fluid pressure control valve according to claim 22 wherein a part of said passage betweenv said first and third chambers forms a part of said one exhaust passage connected to said third chamber, and said exhaust valve is arranged to control uid iiow in such a manner that when the pressure control valve controlling said passage between said first and third chambers is open, said exhaust valve controlling exhaust flow from said third chamber through said last mentioned exhaust passage is closed and vice versa.

24. A fluid pressure control valve according to claim 22 wherein a part of said passage between said first and third chambers forms a part of said one exhaust passage connected to said third chamber, said exhaust valve is arranged to control iiuid flow in such a mann-er that when the pressure control valve controlling said passage between said first and third chambers is open, said exhaust valve controlling exhaust iiow from said third chamber through said last mentioned exhaust passage is closed and vice versa, and means are provided for alternately unseating said pressure control valve and said exhaust valve.

25. A fluid pressure control valve according to claim 22 wherein the area of the port controlled by the valve seat around the passage through the hollow valve member is materially less than the area of the piston valve member on the side thereof remote from such valve seat.

LAWRENCE H. GARDNER.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 624,890 Batchelor May 9, 1899 2,097,201 Renkenberger Oct. 26, 1937 2,157,240 Keel May 9, 1939 2,409,517 Schmit Oct. 15, 1946 FOREIGN PATENTS Number Country Date 586,501 Great Britain Mar. 20, 1947 

